This invention relates generally to a method for forming suspended microstructures and more specifically to a method for forming suspended microstructures using ion implantation.
Semiconductor devices continue to shrink in size while growing exponentially in function. One class of small-scale semiconductor devices is microelectromechanical systems (MEMS), which are gaining ever-growing popularity in the microelectronics industry. MEMS are semiconductor device systems that include one or more microstructures, that is, structures of the size on the order of sub-xcexcm to millimeters. MEMS systems typically are fabricated using micromachining technology that includes a number of intricate, and often costly, processing and fabrication steps that are conducted on a very small, microscopic scale.
A variety of MEMS devices, such as microbeams, membranes, capacitive-type sensors, microhinges, and microvalves, utilize or are fabricated from suspended microstructures. Such suspended microstructures are typically formed using micromachining technology that includes grinding and polishing processes or wet chemical etching processes. However, grinding and polishing processes may be prone to wafer breakage and may result in microstructures having non-uniform thicknesses over the cavities from which they are suspended. Wet chemical etching processes may be time consuming, thus increasing production costs and reducing throughput, and may leave an etch stop layer behind. The etch stop layer may not be desirable and may need to be removed by a non-selective etch.
Accordingly, a need exists for a method for forming suspended microstructures from a monocrystalline substrate using ion implantation.